<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        h1{
            font-size: 40px;
            color: red;
        }

        div{
            background-color: yellow;
            width: 400px;
            height: 300px;
            text-align: center;
            : 50% ;
        }
    </style>
</head>
<body>

<div>
    <h1>你好</h1>
    <h1>你过来呀</h1>
    <h1>哈哈</h1>

</div>
<br>
<hr>
<div>
    呵呵
</div>
</body>
</html>